Method and device for transferring a solder deposit configuration

ABSTRACT

Method and device for transferring a solder deposit configuration having multiple solder deposits onto a terminal surface configuration of a contact surface of a substrate ( 36 ) using a removal of multiple solder deposits from a solder deposit reservoir ( 25 ) accommodated in a solder deposit receptacle unit ( 11 ) via an isolation unit ( 12 ), which is implemented like a template and is situated above the solder deposit reservoir, to implement the solder deposit configuration implemented corresponding to the terminal surface configuration, and using a subsequent transfer of the solder deposit configuration onto the terminal surface configuration of the substrate, the solder deposit reservoir being impinged by partial vacuum through template openings ( 15 ) of the isolation unit to transfer the solder deposits from the solder deposit reservoir into the isolation unit, the solder deposit reservoir ( 25 ) being ventilated via a floor wall ( 20 ) situated diametrically opposite the isolation unit during the partial vacuum impingement ( 27 ) by the isolation unit ( 12 ).

CROSS-REFERENCE TO RELATED PATENT APPLICATIONS

This is a divisional application of U.S. patent application Ser. No.11/666,188, Mar. 11, 2008, now U.S. Pat. No. 7,762,446 which representsthe national stage entry under 35 U.S.C. §371(c) of PCT Application No.PCT/DE05/01698, filed on Sep. 26, 2005, which claims priority to GermanPatent Application No. 2004-051-983.8 filed on Oct. 25, 2004. The fullcontents of these applications are incorporated by reference herein asis set forth in their entirety.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH

Not applicable.

BACKGROUND OF THE INVENTION

The present invention relates to a method for transferring a solderdeposit configuration having multiple solder deposits on a terminalsurface configuration of a contact surface of a substrate using aremoval of multiple solder deposits from a solder deposit reservoiraccommodated in a solder deposit receptacle unit via an isolation unit,which is implemented like a template and is situated above the solderdeposit reservoir, to form a solder deposit configuration implementedaccording to the terminal surface configuration, and using a subsequenttransfer of the solder deposit configuration to the terminal surfaceconfiguration of the substrate, the solder deposit reservoir beingimpinged by partial vacuum through template openings of the isolationunit to transfer the solder deposits from the solder deposit reservoirinto the isolation unit. Furthermore, the present invention relates to adevice especially suitable for performing the method.

In a method used until now for transferring a solder depositconfiguration, the isolation unit connected to a partial vacuum unit ismoved into the solder deposit receptacle unit to remove a number ofisolated solder deposits corresponding to the template openings in sucha way that air enters, as a result of the partial vacuum impingement ofthe isolation unit, into the solder deposit receptacle unit via a framegap implemented between the circumference of the isolation unit and adelimitation wall of the solder deposit receptacle unit. A correspondingperipheral air inflow into the solder deposit reservoir accommodated inthe solder deposit receptacle unit results therefrom, with the resultthat an agglomeration of solder deposits occurs in the center of theradial air inflow. Because of this central solder deposit accumulation,depending on the planar extension of the isolation unit, there may be nosolder deposits or solder deposits in an inadequate number diametricallyopposite the decentralized areas of the isolation unit, so that due tothe partial vacuum impingement of the isolation unit, not all templateopenings are occupied by solder deposits.

SUMMARY OF THE INVENTION

The object of the present invention is therefore to refine the methodand a device used for performing the method so that the occurrence offlaws described above during the occupation of the template openings ofthe isolation unit is avoided as much as possible.

This object is achieved by a method having the features of Claim 1.

In the method according to the present invention, the solder depositreservoir is ventilated during the partial vacuum impingement by theisolation unit via a floor wall situated diametrically opposite theisolation unit.

Due to the ventilation of the solder deposit reservoir from a sidediametrically opposite the plane of the isolation unit, as a result ofthe partial vacuum impingement of the isolation unit, a uniformly planarinflow of air into the solder deposit reservoir may occur. An occurrenceof a radial air inflow into the solder deposit reservoir with thedisadvantageous central accumulation of the solder deposits is avoided.Instead, due to the planar inflow of air from the bottom, which thusoccurs essentially coaxially to the partial vacuum impingement of theisolation unit, the relative configuration of the solder deposits in thesolder deposit reservoir is not disadvantageously influenced. Therefore,a distribution of the solder deposits in the solder deposit reservoirwhich is plane-parallel to the isolation unit before the partial vacuumimpingement of the isolation unit is essentially maintained during thepartial vacuum impingement. Therefore, solder deposits are alwaysprovided in a sufficient number also diametrically opposite theexternal, decentralized areas of the isolation unit, so that theformation of the flaws described above, i.e., template openings of theisolation unit which are unoccupied or incorrectly occupied, may notoccur.

To achieve complete occupation of the template openings of the isolationunit in particular even when a relatively low partial vacuum is applied,it may be advantageous to perform the ventilation of the floor wall inpartial areas of the floor wall in such a way that different partialareas of the floor wall are ventilated sequentially beginning with afirst partial area. It is thus ensured that the vacuum forces acting onthe individual solder deposits are sufficiently large even in the eventof a relatively low partial vacuum to move the solder deposits into thetemplate openings.

One possibility for the successive ventilation of partial areas of thefloor wall comprises performing the ventilation using an airintroduction unit movable along the floor wall.

It may prove advantageous for influencing the distribution of the solderdeposits in the solder deposit reservoir to perform the ventilationusing elevated pressure. In particular to prevent disadvantageousimpairment of the vacuum effect acting on the solder deposits because ofthis, it may be advantageous to perform the ventilation at elevatedpressure with a time offset to the partial vacuum impingement of theisolation unit, i.e., for example, to perform the elevated pressureimpingement of the solder deposit reservoir during a phase in whichthere is no vacuum impingement of the isolation unit.

In a preferred variation of the method, the isolation unit isadditionally impinged by oscillations during the partial vacuumimpingement, to thus mechanically support the positioning of theindividual solder deposits in the template openings of the isolationunit. For this purpose, an oscillation impingement of the isolation unitcoaxial to the direction of the partial vacuum impingement has beenshown to be especially effective.

The device according to the present invention for transferring a solderdeposit configuration has a solder deposit receptacle unit, which isprovided with an at least partially air-permeable floor wall forsituating the solder deposit reservoir.

In an advantageous embodiment of the device, the floor wall is providedwith an air introduction unit, whose position to the floor wall ischangeable, to introduce air into the solder deposit receptacle unit.

It may prove to be especially advantageous for influencing thedistribution of the solder deposits in the solder deposit reservoir ifthe air introduction unit has a connection unit for connecting acompressed air source.

In a preferred embodiment of the device, the isolation unit is providedwith a vibration oscillator, which allows the isolation unit to beimpinged by mechanical oscillations. The vibration oscillator may beimplemented as an ultrasonic generator, for example.

BRIEF DESCRIPTION OF THE DRAWINGS

In the following, preferred variations of the method and embodiments ofdevices especially suitable for performing the method are explained ingreater detail on the basis of the drawing.

FIG. 1 shows a first variation of the method with illustration of afirst embodiment of the device;

FIG. 2 shows a second variation of the method with illustration of asecond embodiment of the device;

FIG. 3 shows an isolation unit of the device directly before thetransfer of a solder deposit configuration to a contact substrate;

FIG. 4 shows the transfer of the solder deposit configuration to acontact surface configuration of the contact substrate;

FIG. 5 shows the contact substrate having the solder depositconfiguration situated thereon after completed transfer;

FIG. 6 shows a variation of the transfer of the solder depositconfiguration received by the isolation device;

FIG. 7 shows the contact substrate having the solder depositconfiguration situated thereon after completed transfer.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 shows a transfer device 10 having an isolation unit 12 situatedabove a solder deposit receptacle unit 11. The isolation unit 12 has acarrier plate 13, implemented as air-permeable and rigid, which isprovided on its side facing toward the solder deposit receptacle unit 11with an isolation template 14. The isolation template 14 is providedwith multiple template openings 15, which are implemented as throughopenings and are distributed in a defined planar configuration over thecarrier plate, in particular as a perforation matrix 28, perpendicularto the plane of the drawing. The isolation template 14 is connected viaa fastener 16, which is implemented as annular or frame-like, to ahousing part 17, which, together with the carrier plate 13, defines ahousing chamber 18, which is provided with a connection unit 19 forconnection to a vacuum pump (not shown in greater detail here). As mayalso be seen from FIG. 1, the housing part 17 of the isolation unit 12is equipped with an ultrasonic generator 20, which causes the isolationunit 14 to oscillate during operation.

The solder deposit receptacle unit 11 has a floor wall 20, implementedas air-permeable, and a side wall 21, implemented in the present case asa hollow cylinder, so that the solder deposit receptacle unit 11 isimplemented in the present case as essentially cup-like. In theexemplary embodiment shown, the floor wall 20 is accommodated betweentwo fasteners 22, 23, implemented as annular or frame-like, toaccommodate the floor wall 20 and/or to connect the floor wall 20 to theside wall 21.

As may also be seen from FIG. 1, a solder deposit reservoir 25comprising multiple solder deposits 26, which are implemented in thepresent case as spherical solder material, is located in a receptaclespace 24 of the solder deposit receptacle unit 11 defined by the floorwall 20 and the side wall 21.

FIG. 1 shows the transfer device 10 during a first phase for receivingthe solder deposits 26 accommodated unordered in the solder depositreceptacle unit 11 using the isolation unit 12. For this purpose, avacuum is applied to the isolation unit 12 situated in the removalposition above the solder deposit receptacle unit 11 via the connectionunit 19, so that the partial vacuum current 27 indicated in FIG. 1results due to the partial vacuum. Due to the partial vacuum current 27,the individual solder deposits 26, which were located in unordereddistribution on the floor wall 20 before application of the partialvacuum current 27, are moved toward the isolation template 14 of theisolation unit 12 as shown by the illustration in FIG. 1. In theexemplary embodiment illustrated in FIG. 1, the floor wall 20 isimplemented as porous over its entire surface covered by the perforationmatrix 28 of the isolation template 14, for example, as a perforatedplate. Induced by the partial vacuum current 27, an essentiallyuniformly distributed ventilation flow 29 results over the surface ofthe floor wall 20, with the result that a corresponding movementactivity of the solder deposits 26 distributed uniformly over thesurface of the floor wall 20 occurs. The solder deposits 26 are movedtoward the isolation template 14 and upon positioning against thetemplate openings 15, which have a smaller diameter than the solderdeposits 26, are held on the isolation template 14 as a result of thepartial vacuum. The implementation of relative positioning of the solderdeposits 26 diametrically opposite the template openings 15 may besupported by an oscillation impingement of the isolation unit 12 via theactivation of the ultrasonic generator 30 situated on the housing part17.

FIG. 2 shows a transfer device 31 in an embodiment varied in relation tothe illustration in FIG. 1, which, in contrast to the transfer device10, has a solder deposit receptacle unit 32 which is provided with anair introduction unit 33 situated on the ventilation side of the floorwall 20. As indicated by the double arrow 34 in FIG. 2, the airintroduction device 33 is movable in a plane parallel to the floor wall20. Depending on the implementation of the air introduction device 33and/or the planar shape of the floor wall 20 and/or the isolationtemplate 14, to whose planar shape the planar shape of the floor wall 20is tailored, the travel motion of the air introduction device 33 may beimplemented moving back and forth translationally or also as a dual-axismovement. Thus, for example, if the floor wall 20 is formed in the shapeof a circular disk, it is advantageous to apply the travel movement ofthe air introduction device 33 in a spiral shape, to impinge the entiresurface of the floor wall 20 using a ventilation flow 35 starting fromthe periphery or the center of the floor wall 20. It is clear from theillustration in FIG. 2 that due to the regional impingement of the floorwall 20 with the ventilation flow induced by the partial vacuum current27, the template openings 15 of the isolation template 14 are occupiedby solder deposits 26 in accordance with the ventilated areas.

FIG. 3 shows the isolation unit 12 having the template openings 15 ofthe isolation template 14 occupied by solder deposits 26 during thearrangement above a contact substrate 36, which may be implemented as awafer, for example, and has multiple contact surfaces 37. The contactsurfaces 37 of the contact substrate 36 have a contact surfaceconfiguration 38, which corresponds to a solder deposit configuration 39defined by the perforation matrix 28 of the isolation template 14. Tomaintain the solder deposit configuration 39, the partial vacuumimpingement to implement the partial vacuum current 27 is maintainedeven after completed removal of the solder deposits 26 from the solderdeposit receptacle unit. Therefore, the isolation unit 12 may also beused as a handling unit for transportation of the solder deposits 26removed from the solder deposit receptacle unit 32 and relativeorientation of the solder deposit configuration 39 to achieve thesuperposition with the contact surface configuration 38 shown in FIG. 3.The axial control for the relative orientation of the solder depositconfiguration 39 to the contact surface configuration 38 may besupported in a known way by an image processing unit (not shown ingreater detail here).

As FIG. 3 also shows, the contact substrate 36 is situated on areceptacle unit 40 having a receptacle plate 41 and a counter plate 42,which accommodate a flexible seal membrane 43 between them. The sealmembrane 43 is accommodated peripherally between two housing rings 44,45. In the configuration shown in FIG. 3, the receptacle unit 40 issituated on a bonding table 46, which is provided with a partial vacuumline 47 for the temporarily fixed positioning of the receptacle unit 40and/or the contact substrate 36 during the orientation procedure for therelative positioning of the solder deposit configuration 39 in relationto the contact surface configuration 38.

After completed relative positioning, the isolation unit 12 having theisolation template 14 is moved toward the housing ring 44 of thereceptacle unit 40, so that a terminated contact space 48 (FIG. 4) isformed between the receptacle unit 40 and the isolation unit 12. Togenerate the contact pressure necessary for a bonding procedure, avacuum is generated in the contact space 48 via a vacuum connection unit49 implemented in the housing ring 44 here after the vacuum impingementof the receptacle unit 40 by the partial vacuum line 47 is ended.Subsequently, the contact substrate 36 is heated via the receptacle unit40 to produce a thermal bond between the solder deposits 26 and thecontact surfaces 37 of the contact substrate 36 in a reflow method.

The vacuum generated in the contact space 48 allows the build-up of thecontact pressure necessary for the contacting, without pressure forceshaving to be applied externally to the device. Therefore, the necessityof dimensioning the device appropriately is also dispensed with.Furthermore, after prior relative positioning of the solder depositconfiguration 39 in relation to the contact surface configuration 38during the partial vacuum impingement of the contact space 48, noseparate guide units are necessary to fix the exact relative positioningin the contact pressure phase. Because of the flexibility of the sealmembrane 43, parallelism deviations between the surfaces of theisolation template 14 and the contact substrate 36 facing toward oneanother, which may be present before the partial vacuum impingement, arecompensated for, so that co-planarity of the surfaces and thus a contactgap width which is as constant as possible may be ensured in the contactpressure phase. The partial vacuum impingement of the contact space 48particularly ensures that the relative positioning is maintained duringthe reflow. A flux application present between the solder deposits 26and the contact surfaces 37 is displaced due to the contact pressure, sothat direct contact between the solder deposits 26 and the contactsurfaces results immediately at the beginning of the reflow phase.

By turning off the vacuum applied via the vacuum connection unit 49, thereceptacle unit 40 is transferred to the bonding table 46 again aftercompleted contacting, as shown in FIG. 5.

As an alternative to the procedure described with reference to FIGS. 3,4, and 5, in which a flexible seal membrane 43 is used for the transferof the solder deposit configuration 39 situated on the isolationtemplate 14 of the isolation unit 12 to the contact surfaceconfiguration 38 of the contact substrate and/or to generate the contactpressure necessary to perform the bonding procedure, a bonding table 50shown in FIGS. 6 and 7 has a lift unit 51, having a lift table 52extendable from the plane of the bonding table 50. A seal to generate agas-tight contact space 55 (FIG. 6) between the isolation unit 12 andthe bonding table 50 is made possible by an elastic seal 54 situated ina table surface 53 peripherally to the contact substrate 36, which maybe implemented as an O-ring seal, for example. The flexibility of theseal 54 allows, in cooperation with the partial vacuum impingement ofthe contact space 55, the effects already described in detail withreference to FIG. 4. The impingement of the contact space 55 usingpartial vacuum is performed via a partial vacuum line 56 implemented inthe bonding table 50.

1. A method for transferring multiple solder deposits to a terminalsurface configuration of a contact surface of a substrate, the methodcomprising: placing an isolation unit on a solder deposit receptacleunit, wherein the isolation unit includes a template with templateopenings that correspond to a solder deposit configuration and whereinthe solder deposit receptacle unit includes a solder deposit reservoirwith an air-permeable floor wall and an air suction unit whosepositioning relative to the air-permeable floor wall is changeable;transferring multiple solder deposits from the solder deposit reservoirto the template openings of the isolation unit by a partial vacuumimpingement of the solder deposit reservoir through the templateopenings and moving the air suction unit to regionally suck air throughthe air-permeable floor wall; and transferring the solder depositconfiguration on the isolation unit to the substrate to establish theterminal surface configuration thereon.
 2. The method according to claim1, wherein sucking air through the air-permeable floor wall is performedin partial areas of the air-permeable floor wall in such a way thatdifferent areas of the air-permeable floor wall are ventilated inchronological sequence, beginning with a first partial area.
 3. Themethod according to claim 1, further comprising the step of ventilatingthe solder deposit reservoir using elevated pressure during a phase inwhich there is no partial vacuum impingement.
 4. The method according toclaim 3, wherein the ventilation using elevated pressure is performedwith a time offset to the partial vacuum impingement of the isolationunit.
 5. The method according to claim 1, wherein the isolation unit isadditionally impinged by oscillations during the partial vacuumimpingement.
 6. The method according to claim 5, wherein the oscillationimpingement of the isolation unit is performed coaxially to thedirection of the partial vacuum impingement.
 7. The method according toclaim 1, wherein the isolation unit further includes a vacuum connectionunit for connect to a vacuum unit for creation of a partial vacuum inthe isolation unit.